This application claims the benefit of Korean Application No. 98-54151, filed Dec. 10, 1998, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a fluid jetting apparatus and a process for manufacturing the same, and more particularly, to a fluid jetting apparatus for a print head which is employed in output apparatuses such as an ink-jet printer, a facsimile machine, etc. to jet fluid through a nozzle, and a manufacturing process thereof.
2. Description of the Related Art
A print head is a part or a set of parts which are capable of converting output data into a visible form on a predetermined medium using a type of printer. Generally, such a print head for an ink jet printer, and the like, uses a fluid jetting apparatus which is capable of jetting the predetermined amount of fluid through a nozzle to an exterior of a fluid chamber holding the fluid by applying a physical force to the fluid chamber.
According to methods for applying physical force to the fluid within the fluid chamber, the fluid jetting apparatus is roughly grouped into a piezoelectric system and a thermal system. The piezoelectric system pushes out the ink within the fluid chamber through a nozzle through an operation of a piezoelectric element which is mechanically expanded in accordance with a driving signal. The thermal system pushes the fluid through the nozzle by means of bubbles which are produced from the fluid within the fluid chamber by the heat generated by an exothermic body. Recently, also, a thermal compression system has been developed, which is an improved form of the thermal system. The thermal compression system is for jetting out the fluid by driving a membrane by instantly heating a vaporizing fluid which acts as a working fluid.
FIG. 1 is a vertical sectional view of a fluid jetting apparatus according to a conventional thermal compression system. The fluid jetting apparatus of the thermal compression system includes a heat driving part 10, a membrane 20, and a nozzle part 30.
A substrate 11 of the heat driving part 10 supports the heat driving part 10 and the whole structure that will be constructed later. An insulated layer 12 is diffused on the substrate 11. An electrode 14 is made of a conductive material for supplying an electric power to the heat driving part 10. An exothermic body 13 is made of a resistive material having a predetermined resistance for expanding a working fluid by converting electrical energy into heat energy. Working fluid chambers 16 and 17 contain the working fluid, to maintain a pressure of the working fluid which is heat expanded, are connected by a working fluid introducing passage 18, and are formed within a working fluid barrier 15.
Further, the membrane 20 is a thin layer which is adhered to an upper portion of the working fluid barrier layer 15 and working fluid chambers 16 and 17 to be moved upward and downward by the pressure of the expanded working fluid. The membrane 20 includes a polyimide coated layer 21 and a polyimide adhered layer 22.
Jetting fluid chambers 37 and 38 are chambers which are formed to enclose the jetting fluid. When the pressure is transmitted to the jetting fluid through the membrane 20, the jetting fluid is jetted only through a nozzle 35 formed in a nozzle plate 34. Here, the jetting fluid is the fluid which is pushed out of the jetting fluid chambers 37 and 38 in response to the driving of the membrane 20, and is finally jetted to the exterior. A jetting fluid introducing passage 39 connects the jetting fluid chambers 37 and 38. The jetting fluid chambers 37 and 38 and the jetting fluid introducing passage 39 are formed in a jetting fluid barrier layer 36. The nozzle 35 is an orifice through which the jetting fluid held using the membrane 20 and the jetting fluid chambers 37 and 38 is emitted to the exterior. Another substrate 31 (see FIGS. 4A and 4B) of the nozzle part 30 is temporarily employed for constructing the nozzle part 30, and should be removed before the nozzle part 30 is assembled.
FIG. 2 shows a process for manufacturing the fluid jetting apparatus according to a conventional roll method.
As shown in FIG. 2, the nozzle plate 34 is transferred from a feeding reel 51 to a take-up reel 52. In the process of transferring the nozzle plate 34 from the feeding reel 51 to the take-up reel 52, a nozzle is formed in the nozzle plate 34 by laser processing equipment 53. After the nozzle is formed, air is jetted from an air blower 54 so as to eliminate extraneous substances attached to the nozzle plate 34. Next, an actuator chip 40, which is laminated on a substrate to the jetting fluid barrier, is bonded with the nozzle plate 34 by a tab bonder 55, and accordingly, the fluid jetting apparatus is completed. The completed fluid jetting apparatuses are wound around the take-up reel 52 to be preserved, and then sectioned in pieces in the manufacturing process for the print head. Accordingly, each piece of the fluid jetting apparatuses is supplied into the manufacturing line of a printer.
The process for manufacturing the fluid jetting apparatus according to the conventional thermal compression system will be described below with reference to the construction of the fluid jetting apparatus shown in FIG. 1.
FIGS. 3A and 3B are views for showing a process for manufacturing the heat driving part and FIG. 3C is a view for showing a process for manufacturing the membrane on the heat driving part of the conventional fluid jetting apparatus. FIGS. 4A to 4C are views for showing the process for manufacturing the nozzle part.
In order to manufacture the conventional fluid jetting apparatus, the heat driving part 10 and the nozzle part 30 should be manufactured separately. Here, the heat driving part 10 is completed as the separately-made membrane 20 is adhered to the working fluid barrier layer 15 of the heat driving part 10. After that, by reversing and adhering the separately-made nozzle part 30 to the membrane 20, the fluid jetting apparatus is completed.
FIG. 3A shows a process for diffusing the insulated layer 12 on the substrate 11 of the heat driving part 10, and for forming an exothermic body 13 and an electrode 14 on the insulated layer 12 in turn. Referring to FIG. 3B, working fluid chambers 16 and 17 and a working fluid passage 18 are formed by performing an etching process of the working fluid barrier layer 15 through a predetermined mask patterning. More specifically, the heat driving part 10 is formed as the insulated layer 12, the exothermic body 13, the electrode 14, and the working fluid barrier layer 15 are sequentially laminated on the substrate 11 (which is a silicon substrate). In such a situation, the working fluid chambers 16 and 17 which are filled with the working fluid to be expanded by heat, are formed on an etched portion of the working fluid barrier layer 15. The working fluid is introduced through the working fluid introducing passage 18.
FIG. 3C shows a process for adhering the separately-made membrane 20 to the upper portion of the completed heat driving part 10. The membrane 20 is a thin diaphragm, which is to be driven toward the jetting fluid chamber 37 (see FIG. 1) by the working fluid which is heated by the exothermic body 13.
FIG. 4A shows a process for manufacturing a nozzle 35 using the laser processing equipment 53 (shown in FIG. 2) after an insulated layer 32 and the nozzle plate 34 are sequentially formed on a substrate 31 of the nozzle part 30. FIG. 4B shows a process for forming the jetting fluid barrier layer 36 on the upper portion of the construction shown in FIG. 4A, and jetting fluid chambers 37 and 38 and the fluid introducing passage by an etching process through a predetermined mask patterning. FIG. 4C shows a process for exclusively separating the nozzle part 10 from the substrate 31 of the nozzle part 30. The nozzle part 30 includes the jetting fluid barrier layer 36 and the nozzle plate 34. On the etched portion of the jetting fluid barrier layer 36, the jetting fluid chambers 37 and 38 filled with the fluid to be jetted are formed. The jetting fluid such as an ink, or the like, is introduced through the jetting fluid introducing passage 39 (see FIG. 1) for introduction of the jetting fluid. The nozzle 35 is formed on the nozzle plate 34 to be interconnected with the jetting fluid chamber 37, so that the fluid is jetted through the nozzle 35. The nozzle part 30 is manufactured by the processes that are shown in FIGS. 4A to 4C. First, the nozzle plate 34 inclusive of the nozzle 35, is formed on the substrate 31 having the insulated layer 32 through an electroplating process. Next, the jetting fluid barrier layer 36 is laminated thereon, and the jetting fluid chambers 37 and 38 and the jetting fluid introducing passage 39 are formed through a lithographic process. Finally, as the insulated layer 32 and the substrate 31 are removed, the nozzle part 30 is completed. The completed nozzle part 30 is reversed, and then adhered to the membrane 20 of a membrane-heat driving part assembly which has been assembled beforehand. More specifically, the jetting fluid barrier 36 of the nozzle part 30 is adhered to the polyimide coated layer 21 of the membrane 20.
The operation of the fluid jetting apparatus according to the thermal compression system will be described below with reference to the construction shown in FIG. 1.
First, an electric power is supplied through the electrode 14, and an electric current flows through the exothermic body 13 connected to the electrode 14. Since the exothermic body 13 generates heat due to its resistance, the fluid within the working fluid chamber 16 is subjected to a resistance heating, and the fluid starts to vaporize when the temperature thereof exceeds a predetermined temperature. As the amount of the vaporized fluid increases, the vapor pressure accordingly increases. As a result, the membrane 20 is driven upward. More specifically, as the working fluid undergoes a thermal expansion, the membrane 20 is pushed upward in a direction indicated by the arrow in FIG. 1. As the membrane 20 is pushed upward, the fluid within the jetting fluid chamber 37 is jetted out toward an exterior through the nozzle 35.
Then, when the supply of electric power is stopped, the resistance heating of the exothermic body 13 is no longer generated. Accordingly, the fluid within the working fluid chamber 16 is cooled to a liquid state, so that the volume thereof decreases and the membrane 20 recovers its original shape.
Meanwhile, a conventional material of the nozzle plate 34 is mainly made of nickel, but the trend in using the material of a polyimide synthetic resin has increased recently. When the nozzle plate 34 is made of the polyimide synthetic resin, it is fed in a reel type. The fluid jetting apparatus is completed by the way a chip laminated from the silicon substrate to the jetting fluid barrier layer 36 is bonded on the nozzle plate 34 fed in the reel type.
According to the conventional fluid jetting apparatus and its manufacturing process, however, since the heat driving part, the membrane, and the nozzle part have to be separately made before such are adhered to each other by three adhering processes, the productivity has been decreased. Further, since the adhesion between the heat driving part and the membrane, and between the membrane and the nozzle part are often unreliable, the working fluid and the jetting fluid often leak, so that a fraction defective has been increased, and the reliability and quality of the fluid jetting apparatus has been deteriorated.
The present invention has been made to overcome the above-described problems of the prior art, and accordingly it is an object of the present invention to provide a fluid jetting apparatus and a manufacturing process thereof capable of improving the reliability, quality and the productivity of the fluid jetting apparatus by sequentially laminating a heat driving part, a membrane, and a nozzle part to form the fluid jetting apparatus, instead of adhering the same to each other.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The above and other objects are accomplished by a method of manufacturing a fluid jetting apparatus according to the present invention, including: (1) forming a heat driving part having a sacrificial layer; (2) forming a membrane on the heat driving part which includes the sacrificial layer; (3) forming a nozzle part on the membrane; and (4) removing the sacrificial layer.
The step (1) includes: (i) forming an electrode and an exothermic body on a substrate; (ii) laminating a working fluid barrier on the electrode and the exothermic body, and forming a working fluid chamber in the working fluid barrier; (iii) forming a protective layer on the working fluid barrier, the electrode, and the exothermic body; (iv) forming a sacrificial layer on the protective layer and within the working fluid chamber at the same height as the working fluid barrier.
Further, the step (1) may otherwise include: (i) forming an electrode and an exothermic body on a substrate; (ii) forming a plane layer on the substrate at the same height as the electrode and the exothermic body combined; (iii) laminating a protective layer on the electrode and the plane layer; (iv) laminating the working fluid barrier on the protective layer, and forming a working fluid chamber in the working fluid barrier; and (v) forming the sacrificial layer on the protective layer and within an interior of the working fluid chamber at the same height as the working fluid barrier.
The step (2) is performed through a spin coating process.
The step (3) includes: (i) laminating a jetting fluid barrier on the membrane, and forming a jetting fluid chamber in the jetting fluid barrier; and (ii) laminating a nozzle plate on the jetting fluid barrier, and forming a nozzle in the nozzle plate. The nozzle plate is laminated through a process for laminating a dry film.
The above and other objects of the present invention may further be achieved by providing a fluid jetting apparatus including a heat driving part which generates a driving force, a nozzle part having a jetting fluid chamber interconnected to an exterior of the fluid jetting apparatus through a nozzle, and a membrane which transmits the driving force generated from the heat driving part to the nozzle part, wherein the heat driving part comprises: an electrode and an exothermic body formed on a substrate; a plane layer formed on the substrate at the same height as the electrode and the exothermic body combined; a protective layer laminated on the plane layer; and a working fluid barrier laminated on the protective layer, and provided with the working fluid chamber for holding a working fluid which is expanded by the exothermic body to generate the driving force.